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Fetal Fetal Fibrinogen Time (Fetal Measurement of Clotting Time)

Published: August 9, 2026Updated: August 16, 2026

This test measures how long it takes for fetal blood to clot, which helps assess fetal blood health during pregnancy. It’s often used in specialized prenatal care to monitor conditions like hemolytic disease of the fetus and newborn (HDFN).

Quick summary

["A longer clotting time may indicate potential bleeding risks in your baby."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
11965-1
Short code
Fet Ft Length US.meas
Synonyms
Fet Ft Length US.meas
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
us-measured
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test if you have a high-risk pregnancy, such as Rh incompatibility, or if there are signs of fetal distress. It helps ensure your baby’s blood clotting system is functioning properly before birth.

What to Expect During the Test

The test involves taking a small blood sample from your baby, usually through a procedure called a fetal blood sampling (also called cordocentesis). You’ll be under mild sedation, and the process is carefully monitored by medical professionals.

How the Results Are Interpreted

Results are compared to standard fetal clotting times. While reference ranges vary by lab, a prolonged time may signal potential bleeding risks, prompting further evaluation. Your provider will discuss findings with you.

Common Reasons for Testing

This test is most commonly performed when there’s concern for conditions like HDFN, where your baby’s red blood cells are destroyed by your immune system, leading to anemia or other complications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Fetal Clotting Time

Frequently asked questions

How often is this test performed during pregnancy?
This test is typically done only in specific high-risk pregnancies, often once or twice during gestation, depending on your medical history and provider’s recommendations. It’s not a routine screening test for all pregnancies.
What are the risks involved with fetal blood sampling?
The procedure carries a small risk of complications, including infection, bleeding, or fetal injury. However, these risks are rare and carefully managed by trained medical professionals. Your provider will discuss potential risks before the test.
Can this test be done without a fetal blood sample?
No, this test specifically requires a direct blood sample from the fetus. Alternative methods, like maternal blood tests, cannot provide the same detailed fetal clotting assessment.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy